Double end center lapping machine



Dec, 1.4, 1948.

G. HOHWART DOUBLE END CENTER LAPPING MACHINE 2 Sheets-Sheet 1 Filed Aug..6, 1945 m m m N I gaf #0 buff.

G. HOHWART DOUBLE END CENTER LAPPING MACHINE Filed Aug. 6 1945 2Sheets-Sheet 2 INVENTOR.

7 420 16 fla n arz BY hand side of Figure l; and,

Patented Dec. 14, 1948 DOUBLE END CENTER LAPPING MACHINE GeorgeHohwart,Detroit, Mich., assignor to N. A.

Woodworth Company, Ferndale, Mich., a corporation of MichiganApplication August 6, 1945, Serial No. 609,145

4 Claims.

This invention relates to lapping machines and I thereon, each headincluding a spindle and av driving motor, the spindles being aligned andeach carrying a lapping instrumentality, the spindles together with thelapping instrumentalities being relatively movable toward and away fromeach other; the provision of .a machine of the type described in whichtheheads are adjustable toward and away from each other whereby torender the machine adjustable to take care of workpieces of differentlengths; the provision of a machine of the type described in which theheads may be of a conventional type commonly employed in drillingapparatus and the frame of the machine is provided with a barformounting the heads in the same manner as the heads are conventionallymounted on the post of a drill press; the provision of a machine of theclass described including means for directing a blast of air against thecenter holes ofthe workpiece at the time the workpiece is applied to themachine and at the time the workpiece is removed from the machine; andthe provision of a machine of the class described including means formechanically cleaning the center holes of the workpieces.

The above being among the objects of the present invention, the sameconsists in certain novel features of construction and combinations ofparts to be hereinafter described with reference to the accompanyingdrawings, and then claimed, having the above and other objects in view.

In the accompanying drawings which illustrate a suitable embodiment ofthe present invention and in which like numerals refer to like partsthroughout the several different views,

Figure 1 is a partially broken, partially sec tioned front elevationalviewof my improved lapping machine;

Figure 2 is an. enlarged end view of my improved machine takenlooking-from the right- Figure 3 is a still further enlarged,fragmentary indicated generally at 24.

front elevational view illustrating the means and method employed indressing the lapping instrumentalities.

The present invention deals with a machine by means of which the centerholes at opposite ends of a workpiece maybe simultaneously lapped in aquick and easy manner and requiring no more time to lap two center holesthan is ordinarily required to lap one. Not only is the machine designedto thus halve the labor cost of lapping center holes in workpieces butthe machine itself is of extremely simple construction and.insuresabsolute concentricity of the two lapped holes in a workpiece, which isan important advantage in itself. The main elements may be of standardparts or assemblies readily obtained on the market at reasonable prices,thereby providing a machine which is economical to build.

Referring now to the accompanying drawings it will be noted that themachine comprises a frame-like structure consisting of a pair ofidentical A-shaped end .members IE1 arranged in spaced and opposedrelation. The lower ends of the members [0 are adapted to rest directlyupon. a fiooror other supporting surface. The upper .ends of the membersID are each provided with a cylindrical'eye l2, between which eyesextends a cylindrical shaft or tube I4 with its opposite ends receivedtherein and securely fixed thereto.

Intermediate its top and bottom each frame member I0 is provided with aninwardly opening cylindrical socket l6, such sockets opening inwardlyand receiving the opposite ends of a larger shaft or tube 18 which isrigidly secured therein. A flat bar 20 is extended between and rigidlyconnected to the lower portions of each frame member I0. Thus the tubes[4 and I8 and the bar 20 serve to rigidly interconnect the frame members[0 and coact therewith to form a rigid framelike structure.

Mounted upon the tube I8 and in a spaced rela tion with respect to eachother are a pair of heads The heads 24 may be and are shown as of awell-known and conventional type manufactured for use as a part of alight, high speed drill press, and each head 24 is z'mounted on the tubel8 in identically the same manner that these heads are mounted on thepost of a drill press when employed in connection therewith. In otherwords each embraces and is clamped to the tube l8 by means of clampingscrews 26 and, when occasion requires, may be shifted axially of thetube 18 by loosening the screws 26 and moving the head to the desiredaxial positionon the tube. Tightening up the screws 26 serves to relocksuch heads in their so adjusted positions.

The two heads 24 are identical except for the minor difierenceshereinafter described, so that a description of one will suffice forboth.

Each head 24 includes an axially movable quill 28, which rotatablysupports therein a spindle 30 as by means IOf bearings 32, but .whichspindle is held against relative axial movement therein. The axes of thequills 28 and spindles 30 are parallel to the axis of the tube l8.effect axial movement of the-quills28,.each-quill is provided with arack 34 thereon in meshing relationship with respect to a pinion 36'fixedto a shaft 38 carried by such head, the rotatable position of whichshaft is controlled by conventional hand wheel 40. At its outer *end,reach spindle 30 is nonrotatably but axially slidably associated with asteppulley 42 through which driving movement of the spindle is imparted.An electric motor carried by-each head 24-is provided with acomplementary stepped pulley 46 connected to the pulley 42 by means of aV-belt 48, thus to provide a driving means for each head.

Each quill 28 has secured thereto adjacent to its inner end a flangemember E50 =to which .is locked, as by means of a threaded connectiontherewith and lock'nut 52, a stud 54 arranged with its axis parallel tothe axis of the quill 28 and spindle 30. The stud 4 projects through anear or lug 56 formed integrally with the-housing of head 24, and nuts-58threaded on the stud 54 on either side oftheear 56 are ordinarilyemployed to limit axial movement of the quill 28 in the head 24.

The inner end of each spindle 30 is provided with a chuck 60 in which isreceived 'a'lapping element 62 the free end "of which is coned orpointed as at 64 at a 60 degree angle to conform to the angle of thecenter holes'tobe'lapped'in a workpiece which-may, for instance, be aplu-g gage such as indicated at 66.

It will, of course, be understood that the axes of the spindles 30 arealigned with ea'ch'other. In this connection, in'the drawings the heads24 are disclosed as arranged'with theushaftso'f the motors 44in'vertical alignment with themes of the quills 28, spindles '30 andtubes "Hand 18,

whereas in actual practice it is preferable "that i the axes of thequills 28 and spindles 3llibe located forwardly, that is towards the Iobserver 'as viewed inFig. 1, out of vertical alignment with-the'planeconnecting the axes of the tubes "P4 and -'l8,'=as this renders themachine more -accessible=to-the operator. The heads are shown 'inthe'position illustrated simply for ease in-illustration. When thespindles arepositioned forwardly as above described, then braces (notshown) maybe :employed between the tubes l4 and each head "-24 andconnected to the heads '24'ata point spaced from the axis of the tubel8,so'as to positively locate and hold the heads with the axes "of "thespindles 30 in aligned relation with respect -'to each other. Inpractice the le'ft hand'head 24 is preferably clamped 'in fixed positionon the tube [8 and the quill 28 is clamped against-axial movement, underwhich circumstances the handle for moving such quill may be removed fromthe machine, and this :-is :the arrangement shown.

In practice, the spindle *30 of theright-h'and head 24 being retractedby'theusual springs provided to rotate the correspondingzhandwheel 8Wina clockwise direction when relieving the pres- In order to 4 sure, theworkpiece such as the plug gage 66 is placed between the lappingelements 62, the center hole at the left-hand end of the workpiece isguided upon the point 64 of the left-hand abrasive element 62 and theoperator then rotates the handwheel to bring the right-hand point 62into the center hole at the right-hand end of the workpiece. .The headsf24lbeing-reversed, the abrasive elements 62 will rotate in'oppositedirections when the motors 44 are energized, so

"that all that is required of the operator is to .lightly (grasp theworkpiece in his hand while positioned between the points 62 and applythe desired pressure to :the handwheel 4!) to cause the abrasiveelements 62 to lap out the center holesin "theworkpiece. When thelapping eleiments 162 have been engaged with the center holes the lengthof time which experience indicatess'hould be sufiicient to properly lapthem out, the operator simply relieves the pressure on the handwheel I40and the ,righthan-d spindle is automatically withdrawn andthjexworkpiece .maythen be removed. Thus, iboth eenteriholes Lintheworkpiece are quickly and.easily ilapped to final-condition and inviewof-"theifact that the abrasive elements r62 are aligned with eachother, the center holes .are :loound .to The ilapped in alignment witheach other, this :overcoming .a problem :which :is constantly gpresentsin construction where only one center 'hole is .lapped at :a time, .asin :the latter :case :extreme :care :must be taken to see s that work isaligned :with the lapping :elements each itime i3. -.:center .hole islapped.

It often occurs that \when hardened work-- pieces are received from :ahardening .operation foreign material has found its way intolone or moreof thecenter :holes of the wor-kpiece a'nd requires to be mechanically:removed before :the :lapp'ing: operation. tIn accordance with the pres-;ent invention and :to facilitate :the removal of suchforeignmaterialfthe outeraen'd o'f thespin'dle 30 :fori-the right-handhead 24 has-.a-.conventional :chuck Ill rmounted :thereon. A renter'drill 1:2, corresponding .in size to the size vof :the :center ZhOlBIin :the work, .is 1 mounted in :the chuck 1'10 so :that the workmen mayremove the'lforeignzmate- :rial ibyrsimply 'pressing that .end 6f the:work- :piece having the :plugged eenter 1 hole son to time .centerdrill t2. .In order to afford-access to the center drill 12therighth-andframe member Hill .is provided with an. opening [4 therein :in align--;ment with the spindle $30.

The lapping elements .62 are 'preferablyrc'ircullar in section andformed from:a Tfine abrasive material. The pointed ends.'641there0f:wear away in service and require frequent dressing. In accordance with:a "further .phase of t'h'e :present invention the dressing of "thepoints :o'f the abrasive elements is accomplished-as follows. A-Zblock811 is rotatably mounted on the -upper tube 1'4 and 1 is held againstaxial :movement :"and in axially adjusted position thereon by means of-a pair of 'clamping collars C82 clamped to :the-tube 14 on either sideof :theblokiBO. The block is-o'f a longitudinally split type having ascrew 84. projected/across the 'line of split-so that upon tightening up'of the screw "84 the -block 80 is caused tobe-ilclampedagainst:rotation to the tube 114. The screw 8'4=isprovided-with a-cross'pin 86 to facilitate the turning of the same.

The' block 80 has fixedthereto one end 'of a -depending plate-1likemember 88 of a greater length and distance between the eenter of the'Atube 1:4 51:0 theza-xes-of:the spindles 30. its

with, respect to the abrasive lower edge," theplate '88' is "provided onits forward face with a transverse block 90 arranged with the upper facethereof perpendicular to the plane of the face of the plate 88 andparallel with the axis of the tube I4. Upon such upper face of the block90 is received the base of a triangular block 92, the sides of which areeach arranged at'an angleof'30-degrees with respect to the plane of itsbore and therefore the upper face of the block 98, this being half theangle of the points 64 of the abrasive elements 62. A rigid downwardextension 94 on the plate 88 is provided at its lower endwith a screw96, best brought out in Fig. 2, the end of which is adapted to contactthe tube I8 when the plate number 88 is swung to one limit of itsposition, thereby to locate the triangular block 92 in proper relationelement 62 for a dressing operation.

The dressing operation, which is best brought out in Fig. 3, isaccomplished by means of a diamond dressing tool consisting of a shortcylindrical base 98 in which is axially secured a cylindrical holder I80having a concentric diamond pointzIIJZ. In practice, the cylinder 98 isrested in flat contacting relationship with respect to the angular facesof the block 92 and against the forward face of the plate 88, the screw98 having been adjusted so that under such circumstances and when thescrew 96 abuts the tube I8, the diamond point I02 and the axis of itsholder I80 are arranged radially of the axis of the abrasive element 62.The spindles 30 being put into rotation, the quills 28 therefore areadvanced until the points 64 of the lapping elements 62 are moved intodressing relationship with respect to the diamond point I02 under thecircumstances stated, the diamond point assembly being first moved alongone of the angularfaces of the triangular block 92 to dress one of thepoints 64 and then being moved over to and moved along the remainingangular face of the number 92 to dress the remaining point 64. It willbe appreciated that in this manner, the points 64 of the lappingelements may be quickly and accurately dressed. When the dressingoperation is completed, the screw 84 is loosened and the plate 88 andassociated parts are swung back out of interfering relation with respectto the work, the screw 84 is tightened to hold them in such position,and the lapping operation may then be resumed.

To further remove foreign material from the centers in the workpiecesbefore the lapping operation and to aid in cleaning out the materialremoved from the workpiece and the abrasive elements during the lappingoperation, after the lapping operation has been completed, it isdesirable to direct the blasts of air into the center holes of theworkpiece. In accordance with the present invention, this isaccomplished by mounting a pair of nozzles IIO, one on each head 24,with its point directed toward the corresponding center hole of theworkpiece in the position which it occupies when supported between theabrasive elements 62, as shown. Each nozzle I I8 is mounted upon one endof a bracket H2 the opposite end of which is clamped to the end of thecorresponding quill by being received on the corresponding stud 54between the corresponding flange 50 and the corresponding lock nut 52 asshown. Each nozzle H0 is connected by a tube H4 to a valve II6 which ismounted upon the right-hand head 24. The valve is mounted by means of amounting stud H8 clamped in a bracket I20 suitably mounted on thehousingfor the right-hand head 24. Air is fed to the valve H6 through .atube I22 connected to any suitable source of air under pressure.

The valve H6 is provided with an operating handle I24 the free end ofwhich is projected into the space between the left-hand nut 58 on thestud 54 for the right-hand head 24 and the lug or flange 56, and suchnut is so adjusted that when its corresponding spindle 38 is advanced tooperative position for lapping operation on a workpiece, the handle I24is released and the valve H6 is closed. When the spindle 30 of theright-hand head 24 is withdrawn to remove the workpiece from between thelapping elements 62 and to insert a new workpiece, the last mentionednut 58 strikes the free end of the handle 24 and opens the valve,thereby admitting air to the tubes H4 and nozzles IIU. Thus, wheneverthe right-hand spindle 30 is withdrawn, to insert a new workpiecebetween the lapping element 62 and a workpiece is positioned to bereceived by the abrasive element 62, the center holes in the oppositeends will receive a blast of air from the nozzles III! and, similarly,when the right hand spindle 38 is withdrawn to remove the workpiece frombetween the abrasive element 62, a blast of air will issue from thenozzles H0 into the center holes thus lapped in the workpiece to aid inremoving any foreign material therein.

From the foregoing will be appreciated that the device of the presentinvention is of extremely simple construction and its main parts may beformed from standard drill heads readily available on the market atrelatively low prices. It will also be appreciated that not only is thedevice of the present invention of value in cutting down the laborcharges required for lapping the center holes one at a time but, inproviding means for lapping both simultaneously, insures absolutealignment of the two center holes and this without requiring any specialfixtures or the like for holding the workpiece during the lappingoperation.

Having thus described my invention what I claim by Letters Patent is:

1. In a lapping machine, in combination, a support, a pair of headsmounted on said support in opposed and spaced relationship, means forlocking said heads in adjustably spaced relation with respect to eachother on said support, a quill axially slidably and nonrotatably carriedby each of said heads in axially aligned relation with respect to eachother, a concentric spindle rotatably supported by each of said quillsand held against relative axial movement with respect thereto, means fordriving said spindles in opposite directions of rotation, a pointedlapping element carried by each of said spindles in axially concentricrelation with respect thereto, means for effecting relative axialmovement between said spindles, an air nozzle directed approximately atthe point of each of said lapping elements, a valve for controlling theflow of air through said nozzles, and means controlled by the relativemovement between said spindles for operating said valve.

2. In a lapping machine, in combination, a support, a pair of headsmounted on said support in opposed and spaced relationship, means forlocking said heads in adjustably spaced relation with respect to eachother on said support, a quill axially slidably and nonrotatably carriedby each of said heads in axially aligned relation with respect to eachother, a concentric spindle rotatably 7 supnontedbyaeach oftsaidquills-and heldagainst :relative axial movement with respect thereto,:meanssfor -driving :said spindles in opposite-threw tions of rotation,a pointed lapping element :cartriefl :byzeachof said sspindles inaxially concentric melajsion ,witnrespect thereto,means for efiectingirelative'axial movement between said spindle an lairnozzlezdirectedaapproximately at the pointof geach :of said lappingelements, a valve :for .0011,- :tro'llingthe flow of air throughsaidnozzleg-and aneansacarried iby oneof said quills en geab1e zwithsaidvalve Whensaid spindlesare retracted srelative 'to one another 'f01'opening said valve.

:3. .In ailapping machine, a pair of opposed-and spaced tool heads eachincluding a spindle and .n1eans:for driving;said spindle, means forsupporting lsaid heads with the spindles in axial alignment with eachother, means for effecting relative (axial movement :between saidspindles, flapping elements carried by said spindles and .having workingends, an air nozzle directed approximatelyatthe Working end of eachlapping e1ement,-.va1ve means "for controlling the flow 'ofairthroughesaid nozzlesn'and means rendered .Qp- :erable by re1ativemovement of the spindles do .qpensaid valve-means.

a. in 1a. flapping machine, il1S111QDDIf}, 2a, pair ;0f xtool headsamount d on .-said's,1 1nmnt in opposed n .vsnaced :relatinn with :reencto 168011 iother,

:axially aligned, mtatable spindlesi caniiedby said heads, rat least[one of :said spindlese mported for lan i-a1 sliding imovement :relativeto zthe other, (means, forraaially advancing rand retractingvsaid:slidable spindle, flapping :elements -,carriedlbyrsaid REEERENQES,GITED The :followingmefezences are of record Lin the file of thispatent:

UNIT D "SIATES 'PATENIFS Judge flu--- June 29, r1942

